Escaping from iCloud Photos

After more than a decade storing photos and videos in iCloud, I decided to download my stuff to my PC and delete the copies at Apple. I figured I'd log into iCloud using my web browser, click the Download link, wait a while for the eighty-plus gigabytes to make their way to my computer, delete the cloud copies, and be done with it. It didn't work out that way. What I expected to take a few minutes…